Life as a Physicist

The New Cup January 17, 2009

I eat lunch almost every day at a cafeteria near by my office. UW has made a big effort in the last two years to make all the garbage that comes out of their cafeteria’s compostable. I met one of the guys who works on that at a party a few months ago. At the time he told me that almost 90% of all the garbage that comes out of the cafeteria is compostable. If they could do soda cups they would be at 95%.

Compostable has a very specific definition. 60 days in a heap and it has to have broken down. One of the out growths of this is “silverware” made out of corn starch. It works great – until you put it in hot soup. The spoons have this very odd behavior of curling up, which makes it difficult to fit in your mouth (or hold soup).

Apparently cups that hold cold liquids are the hardest to make compostable. Hot liquids are easy – you coat the inside of the cup with something, and the cup is good to go. Cold cups, however, have to be coated both inside and outside. The reason is condensation! If the outside isn’t coated, and the cold liquid causes condensation, then the water droplets that form on the outside of the cup will cause the paper part of the cup to disintegrate. Not so good! The fellow at the party told me he had found cups that would be compostable under a 90 day definition, but the UW composting contractor didn’t do 90 days.

Apparently they have solve the problem. Above is the cup. There is a twist, however. I tend to bring these cups back from lunch with some rootbeer in them. After that is gone I fill them with water and use them until the next day. If I eat lunch in my office the next day, the cup will remain in active duty. Sometimes for several days.

No more. These new cups make it almost 48 hours. At that point I noticed a ring of water forming around the cup. :-) Still, it is very cool to see UW have such a high rate of compostable material coming from its cafeterias. The fellow I was talking to said that the next step was to tackle the office work areas. He said this was going to be much more difficult because he had much less control over them. I would imagine so, just looking at all the stuff we throw out! I’m waiting to see!

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1) The UW administration has made several strides in the last month or two in transitioning from paper to electronic forms and documentation. It seems like this is something that should be further along than it is, by now (even though these tools are probably years in the making, from the programming and developing standpoint). Every bit helps, at least.

2) I heard once that Henry Ford made auto upholstery out of soybeans during WWII. I guess it wasn’t an invention that stuck. If there were shortcomings, I wonder what they were? (What would be the car seat version of a curling fork?) :)